Rlip (RLIP76, RALBP1) is a stress-responsive glutathione-electrophile conjugate (GS-E) transporter which is overexpressed in a number of types of cancers (lung, ovary, prostate, skin), but not in all types (breast, liver). Rlip appears to be necessary for cancer cell survival because both in-vitro cell culture and animal tumor studies show that depletion or inhibition of Rlip causes selective toxicity in malignant cells. Additional studies during the funded proposal have shown that differential sensitivity of SCLC to DOX as compared with NSCLC is related to lack of phosphorylation of Rlip by PKC alpha at T297, and that Rlip is required for the DOX-protective effects of PKC alpha. Experimental evidence by others investigators has provided direct links between Rlip and ral, cdc42, clathrin-adapter AP-2, POB1, epsin, grb2/nck, src, insulin, EGF-R, TGF beta, hsf-1 and heat shock proteins. These proteins are key elements of cell membrane plasticity, actin-cytoskeletal regulation and cell migration (cancer cell invasion and metastasis), receptor-ligand-pair endocytosis for signal termination, radiant and oxidant stress-responses, and apoptosis. Our preliminary studies show that Rlip represents an important rate-determining step for termination of EGF or insulin-signaling by endocytosis. The constellation of findings lead us to hypothesized that glutathione-conjugate efflux is a common effector mechanism utilized by membrane-signaling and stress-response pathways necessary for survival of cancer cells. In support of this hypothesis, we have shown regression of established tumors upon Rlip-depletion or inhibition in syngeneic mouse melanoma (Cancer Res. 66:2354, 2006), as well as lung cancer xenografts. We propose specific aims to test hypotheses in the following three areas: 1) In-vivo studies of efficacy, target specificity, and toxicity, 2) Regulation of Rlip by PKC alpha and tyrosine kinases, and 3) Regulation by signaling proteins including POB1 and cdc2 involved in endocytosis.